There are a ton of products on the market to combat porch pirates, and delivery bags are among the most effective. These heavy-duty receptacles usually lock up to any stationary object. You leave them open for the delivery guy, who'll put your package inside, and lock it up before they leave.2 Pretty ingenious, if you ask us.
Pro Tip: If you can, talk with your postman or delivery driver before using one of these products. If you can't, or if the delivery driver is different every time, you might also consider leaving a note with instructions on how to use the bag when you're expecting a package.
Now you might be wondering how secure these bags actually are, and you'd be right to ask. A determined thief probably would be able to get into one with some sharp tools and enough time, but to criticize this solution for being easily defeated is to miss the point. Porch piracy is a crime of opportunity. All you have to do is make it a little harder for the criminal to steal your package, — for it to take a little more time and effort — and they're far more likely to pass you by.